Learn Hardcore Polish: To zależy od czasu, bo mamy wiele spotkań. - That depends on time, because we have many meetings.

In this sentence, to is a neutral, dummy subject and translates as “it.” To zależy is a set phrase meaning “It depends.” You do not say To jest zależy—just To zależy.

Why is it zależy od and not something like zależy na?

The verb zależeć takes the preposition od to mean “depend on”: zależeć od kogo/czego. Using na changes the meaning: zależeć (komuś) na czymś means “to care about” or “to be keen on.” For example: Zależy mi na czasie = “Time matters to me/I’m in a hurry,” not “It depends on time.”

Which case is used after od, and why is it czasu?

Od governs the genitive case. Czas (time) in the genitive singular is czasu, so you get od czasu. Other examples: od pogody (from weather), od ciebie (from you), od decyzji (from the decision).

Is od czasu the most natural choice here, or would Poles say something else?

It’s correct, but in scheduling contexts Poles often specify more precisely:

To zależy od godziny. (It depends on the time/hour.)
To zależy od terminu. (It depends on the date/slot.)
To zależy od tego, kiedy. (It depends on when.) Use od czasu for very general “time,” but od godziny/terminu often sounds more concrete.

Why is it wiele spotkań and not wiele spotkania?

After quantity words like wiele, Polish uses the genitive plural. The noun is spotkanie (a meeting), whose genitive plural is spotkań. So:

Nominative plural: spotkania (meetings)
Genitive plural: spotkań (after wiele/dużo/mało/mnóstwo, etc.)

Can I say dużo/sporo/mnóstwo spotkań instead of wiele spotkań?

Yes:

dużo spotkań = a lot of meetings (very common, neutral/colloquial)
sporo spotkań = quite a lot of meetings (neutral)
mnóstwo spotkań = tons of meetings (emphatic)
wiele spotkań = many meetings (a touch more formal/literary) All still take the genitive plural spotkań.

Do I need to say my mamy, or is mamy enough?

Mamy is enough. Polish drops subject pronouns because the verb ending shows the person. My can be added for emphasis or contrast: My mamy wiele spotkań, a oni nie.

Why is there a comma before bo?

Polish normally requires a comma before bo when it introduces a reason clause. So: …, bo mamy wiele spotkań. No comma after bo.

Is bo too informal? When should I use ponieważ or dlatego że?

Bo is perfectly fine in speech and everyday writing. Ponieważ is more formal/neutral and common in writing. Dlatego że adds a bit of emphasis (“it’s because that…”). All mean “because,” and your sentence works with any of them.

Can I move to after the verb: Zależy to od czasu?

Yes. Zależy to od czasu is correct and sounds a bit more formal or stylistically varied. Both word orders—To zależy od… and Zależy to od…—are common.

Can I drop to and just say Zależy od czasu?

Yes, especially as a short answer or when the subject is clear from context. To zależy (od…) is the default full form; Zależy (od …) is briefer and also natural.

What are the nuances between czas, godzina, termin, and pora?

czas: time in general (abstract)
godzina: a clock time/hour (e.g., 3 p.m.)
termin: an appointed date/deadline/slot
pora: a time/part of day or season (e.g., pora dnia, pora roku) So for scheduling, godzina or termin often fits better than czas.